Method and apparatus for drilling and coring



Oct. 21, 1969 w. D. ELENBURG 3,473,617

METHQD AND APPARATUS FOR DRILLING AND CURING Filed March 20, 1968 Y 2 Sheets-Sheet 1 INVENTOR. 28 WAYLAND D. ELENBURG MARCUS L. BATES Oct. 21, 1969 w. D.- ELENBURG 3,'473;617

METHOD AND APPARATUS FOR DRILLING AND CORING Fiiea March 20, 1968 2 Sheets-Sheet 2 II I 1 .|l n 26 WAYLAND 0. ELENBURG s7 67 MARCUS L. BATES INVENTOR.

United States Patent O US. Cl. 175-215 9 Claims ABSTRACT OF THE DISCLOSURE A bit having a core receiving passageway centrally disposed therethrough, with the centrally arranged passageway being flow connected to the central tubing of the drill stern by a core barrel. The core barrel is rotatably attached to a sub which also attaches the bit to the drill string. Longitudinally extending passageways radially disposed about the core barrel provide a flow of fluid which communicates with the core receiving part of the bit to thereby force the flow of fluid across the diamonds of the bit, and back up through the hole annulus until it is desired to remove the accumulated cores from the barrel. This arrangement enables the bit to be used as a valve means which provides for the removal of the cores in accordance with the above described method.

BACKGROUND OF THE INVENTION In order to obtain geological samples of formations located in the earths structure, a diamond bit is often utilized which enables a cylindrical elongated sample of the formation to be cut into predetermined lengths, called cores. The core passes through the bit as the diamonds on the face of the bit cut away a portion of the formation while the bore hole is being drilled. By using a diamond bit of this design, a more representative sample is obtained as compared to the chip drilling operation wherein large cuttings or chips are relied upon for analysis. In using drilling and coring apparatus of this type, it has been found satisfactory to carry out the coring operation until a core barrel is filled with the individual lengths of cores. During the coring operation, the circulation pattern of the drilling fluid can be traced down through the annulus of the drill string and back up through the hole annulus where the fluid flows into a mud pit. When it is desired to retrieve the cores, the central tubing is opened causing the flow path to change. The drilling fluid continues to travel down through the annulus of the drill string but now is caused to reverse its flow path Where the major flow occurs back up through the central tubing string, carrying the cores therewith to the surface of the earth. In the past art, the cuttings are carried away by the drilling fluid which is directed through passageways located in the drill bit and which communicate with the hole annulus rather than the central portion of the drill. Accordingly, when it is desired to change the circulation pattern, the bit is usually raised or elevated slightly in order to allow the circulation flow path to occur across the 'bit and.

back up through the central passageway, carrying the cores to the surface of the earth. This method of drilling requires tremendous pump pressure inasmuch as the fluid tends to flow along the path of least resistance and is therefore divided into two flow paths, one of which follows the hole annulus, and the other being through the core barrel and up the central tubing.

SUMMARY OF THE INVENTION The present invention comprehends both method and apparatus for carrying out an improved boring and coring operation while forming a bore hole. concentrically arranged drill pipe having a central and annular passageway formed therein for circulating fluid to the bit and for providing a return flow path for obtaining the core is suitably connected to a bit by a combination sub and core barrel. Drilling fluid is forced down through the annulus of the drill pipe or drill string and into close proximity of the diamond or otherwise faced cutting teeth of the bit, with a passageway being radially disposed about the inside central portion of the bit, outwardly of the core receiving annulus. This flow path causes the fluid to be forced with high velocity across the diamonds of the drill bit whereupon the flow then circulates back to the surface of the earth through the hole annulus. Accordingly, the pressure drop across the bit can be controlled by the pressure of the diamonds as they are forced into cutting relationship with respect to the formation. Total flow across the entire bit face maintains the bit cool and clean of debris, and enables the bit to cooperate with the formation with a valve like action. When it is desired to circulate the accumulated cores out of the core barrel, the fluid pressure is increased a predetermined amount while the bit is maintained in drilling relationship, or close contact with the formation to thereby force the major portion of the fluid flow back up the central tubing and pushes the cores to the surface of the earth in an improved manner. All this time the drilling operation continues since this method provides suflicient flow across the bit to protect the diamond face.

The apparatus used in carrying out the present invention includes the before mentioned drill bit and drill string with the bit being connected to the string by a sub. The sub supports a core barrel wherein the core barrel is rotatably secured to the sub with the lower marginal end of the barrel being secured in a non-rotating manner to the core which is being cut to thereby prevent rotation of the barrel and accordingly, improving the quality of the core. A valve means located above the ground and associated with the central tubing, along with the valve-like action of the bit enables the above method to be carried out.

It is therefore a primary object of the present invention to provide a method of obtaining cores from a bore hole by circulating the cores back to the surface of the earth by an improved flow pattern.

Another object of the present invention is the provision of a method which enables coring operations to be carried out by an improved circulation pattern.

A further object of the present invention is the provision of a bit having an improved flow path across a coring or cutting face thereof.

Another object of the present invention is the provision of an improved combination which includes a coring bit, sub, and core barrel and which enables cores to be obtained in an improved manner.

The above objects are attained in accordance with the present invention by the provision of concentrically arranged drill pipe which are connected to a bit and to a non-rotating core barrel which all cooperate together to provide an improved flow path across a bit.

Other objects of the present invention will become apparent to those skilled in the art as the description proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a diagrammatical representation of a cross-section of the earths structure with the present well boring apparatus being positioned therein in order to explain the operation of the invention;

FIGURE 2 is an enlarged cross-sectional view of part of the device seen in FIGURE 1;

FIGURE 3 is a fragmentary cross-sectional view taken along line 33 of FIGURE 2; and

FIGURE 4 is a fragmentary cross-sectional representation of the invention which has been taken along line 4-4 of FIGURE 2.

DETAILED DESCRIPTION OF THE INVENTION FIGURE 1 schematically sets forth a portion of a well drilling apparatus which is in the act of boring a hole into the earths structure 11. Part of the apparatus is located above the surface of the earth as seen at 12 while the remainder of the apparatus is located below the surface of the earth. A high pressure inlet 14 provides a flow of drilling fluid to the uppermost part of a swivel or the like, schematically illustrated by numeral 16, while fluid is returned from the bore hole either by means of a gooseneck 18 or upwardly along the hole annulus 20, depending upon the circulation pattern desired.

A rotatable drill pipe 22 telescopingly receives a longitudinally extending, centrally positioned tubing 24 therewithin, with the drill pipe and tubing being connected together from several joints in the usual manner to form a drill string, as is known to those skilled in the art. At the terminal end of the drill string there is located an outer barrel or sub 25 which carries a diamond bit 26 threadedly attached to the lower depending end thereof. As the bit is rotated by the drill string, a core 28 is formed Within the central aperture of the bit, with the core extending upwardly where it is received within a core barrel 30. The core is broken into uniform lengths such as indicated by the arrow at numeral 32. The core barrel is rotatably attached to the outer barrel or sub by the illustrated journal means 34. The sub includes radially spaced apart passageways extending therethrough for isolating the drilling fluid from the bearing, and to enable the fluid to flow to the drill bit as well as to provide a means for the flow of the accumulated cores back up through the central tubing from time to time.

The rotatable barrel includes spaced apart guide means 33 for maintaining the lower terminal end of the barrel properly aligned with the outer barrel, so as to assure cutting a uniform core. Numerals 36 and 38 indicate spaced apart hypothetical voids, sometime called fractures or fissures. The void 36 has been drilled through or penetrated, and fluid can escape up hole annulus 40 into the void. The bit has also penetrated to a position where it rests on the bottom of the void 38 and drilling fluid can escape thereinto also. The purpose of illustrating the two spaced apart voids will be realized later Looking now to FIGURE 2, wherein an enlarged crosssectional view of the before mentioned outer and inner barrel and bit are shown in detail. It should be understood that the device of FIGURE 2 is connected to the drill string and related apparatus of FIGURE 1. The annulus formed between the inner and outer tubing provides an annular passageway 44 with the core barrel being attached to the sub by means of a bearing such as seen at 46. A collar 48 threadedly engages the core barrel in a manner to capture the bearing therebetween as illustrated at 50. The central portion 52 of the barrel extends downwardly to where it threadedly engages member 54, the depending end of which forms a shoulder at 55. A core breaker 58 commences near shoulder 55 and longitudinally extends in an upward and outward direction for a limited length with respect to the inside peripheral wall surface of the core barrel. The core breaker is preferably circumferentially coextensive with the inside peripheral wall surface for approximately thereof, and is several times longer in length as compared to its width. The vertical distance between the core breaker and the drill bit face determines the length of the individual cores.

Threadedly attached to the lower terminal end of the core breaker member is a cylindrical downwardly converging core catcher housing 60 having a key 62 thereon, and which includes vertically spaced apart splines thereon (not shown) which cooperate with similar spaced apart splines provided on the outside peripheral wall surface of the inverted frusto-conical core catcher 64, the details or which are best seen in FIGURE 3. The lower terminal end portion of the core barrel terminates at 61. The inside face of the drill bit is provided with grooves 67, having a bottom-most portion 68, to thereby leave a passageway between the lower terminal end of the inner barrel and the inside of the bit.

The face of the bit containing the diamonds is generally seen at 66, with the lower inside portion of the bit being provided with the before mentioned grooves which permit the passage of fluid to be forcibly bent across the inside peripheral portion 69 which forms the central aperture of the bit. Accordingly, a passageway 70 is formed between the outer peripheral surface of the various members which forms the core barrel and the inside peripheral wall surface of the outer barrel. The passageway continues as seen at 73 to where it branches into a multiplicity of radially spaced apart passageways 74 which are drilled through the before mentioned sub 42 so as to communicate at 75 with the annular passageway formed by the drill string.

Looking again now to FIGURE 3, in conjunction with FIGURES 1 and 2, wherein the before mentioned core catcher is better illustrated. As seen illustrated therein, as stated above, the core catcher includes a multiplicity of splines which cooperate with similar but oppositely disposed splines 82 formed on the inside peripheral wall surface of core catcher housing 60. Edge portion 84 of the expandable core catcher cooperates with the before mentioned key 62 with the edge portion 84 being slidably and guidably received by the key to thereby enable reciprocation of the core catcher between the limits provided by shoulder 55 and the illustrated position of the core catcher in FIGURE 2.

As seen in FIGURE 4, the lower guide means 33 are each preferably located apart and extend for a limited distance about the annulus 73 so as to leave passageway 72 therebetween. The core barrel rotates against the inside surface area formed by the outwardly directed guide member.

Looking again to FIGURE 1, there is further seen illustrated an inlet valve 92 with leads to the high pressure source of drilling fluid. Outlet valve 94 controls the fluid flow through gooseneck 18 to thereby permit the cores to be caught on a conventional mud screen 96 as the cores are circulated from the bore hole.

In order to catch elongated sections of core which extend from more than five inches in length, the core can alternatively be telescopingly received through the tubing 97, which includes a hinged flange 98 to permit the core catching cylindrical portion 99 to be separated from lower portion 97. Drain apertures 102 are provided in the tubing 97. It will be realized by those skilled in the art that the section 97, 98, 99, and 102 is best placed with its central axis in alignment with the central axis of the tubing 24. i.e., elements 97-102 replace the gooseneck 18.

OPERATION In operation, with the apparatus of the present invention assembled as schematically illustrated in FIG- URE 1, the diamond bit continuously cuts a core. As the core enters the central aperture formed by inside peripheral portion 69 of the bit, the core forces its way upwardly through the core catcher. Since the core catcher has splines which cooperate with the splined inner surface of the core catcher housing, the core barrel remains affixed to the telescopingly received core as the outer barrel rotates about the journal formed by hearing 46.

As the core moves into the barrel, it contacts the core breaker which places a sheer or transverse force on the core body, whereupon the core breaks into uniform lengths with each length of core being accumulated within the core barrel. Since the core breaker and barrel are stationary with respect to the core, the core sample is received in uniform undamaged cylindrical pieces.

During this stage of the operation, drilling fluid enters through inlet 14 where it travels down the annulus of the drill string and at 75 the fluid is diverted into a multiplicity of radially spaced apart passageways 74, where the fluid then travels down through passageway 73 and between the four spaced apart guide means, to where the fluid can now enter annulus 70. From annulus 70 the fluid travels through the passageways formed between the lower depending end 61 of the core barrel and through the multiple grooves 67 formed on the inside lower wall portion of the bit. Since valve 94 of the gooseneck is closed, the fluid must now flow across the diamonds located in the cutting face of the drill bit and back up the hole annulus, carrying the cuttings from the formation with it during its upward travel back to the surface of the earth. The rate of drilling during this time is preferably controlled by observing the pressure drop across the face of the bit rather than by utilizing a weight indicator in the conventional manner. A pressure drop of one hundred and fifty pounds across the face of the drill bit is desirable for most applications, although this figure will usually be changed when encountering unusual formations.

For example, a two and one-eighth inch core, received within a two and one-fourth inch tube, using a four and seven-eighths inch bit attached to a four and one-half inch outside diameter drill pipe provided excellent core samples and exceptionally long bit service when using a drilling fluid flow rate of forty gallons per minute when coring, and one hundred and fifty gallons per minute when circulating the cores to the surface.

The pressure drop across the bit face was adjusted by lifting the bit face free of the formation floor, observing the hydrostatic head at 14, and cautiously setting the bit down until the indicated pressure increased an additional one hundred fifty pounds per square inch, which is the pressure drop across the bit. This value provides a reasonable rate of penetration while maintaining the diamonds of the bit sufficiently cooled and cleaned to thereby prolong the bit life. It should be understood that the recited pressure drop of one hundred and fifty pounds is measured across the cutting surface of the bit, and is exclusive of the hydrostatic head or the friction head of the drill pipe.

While the above operation is described as being carried out by using a liquid drilling mud, it is also contemplated to use air or other compressible fluid, as well as a combination thereof.

When air is used in carrying out the method of the present invention, the flow from the central tubing, and when possible the hole annulus, is restricted to thereby enable a substantial rise in pressure at the drill stem. The flow restriction is then removed from the central tubing by opening the valve associated therewith, whereupon the pressure drop across the cores located in the core barrel forces the cores up through the central passageway of the drill string and through the gooseneck, much like the operation of a piston within a cylinder.

Often it is desirable to use a combination of air and liquid, especially where a stron aquifier is encountered. In this instance, it is preferable to circulate the cores to the surface by restricting the flow of fluid from the bore hole by utilizing the valve action between the drill bit and the formation. Compressed gas is supplied to the drill string annulus, and when the pressure reaches a suitable value, opening of the valve associated with the central tubing enables circulation of the cores to thesurface.

Where air alone fails to properly circulate the cores to the surface, it is possible to admix water or mud with the air which is being used as the return fluid, to thereby provide more body to the fluid in order to better circulate the cores fro-m the core barrel to the gooseneck.

The improved circulation pattern includes forcibly flowing fluid through passageways 67 located on the lower inside face of the bit, wherein the flow is forced to proceed directly across the bit face to where the drilling fluid then returns up the hole annulus. This improved flow pattern causes all of the drilling fluid to be forced across the drilling face, and when encountering voids or fissures, such as seen at 38, escape of drilling fluid into the formation does not result in destruction of the diamonds as usually occurs when using a conventional circulation system. Therefore, even under conditions wherein there is a complete loss of circulation, the improved bit is safely provided with adequate fluid flow thereacross, so long as fluid enters at 92.

Accordingly, by forcibly pumping fluid from inside the bit to an area externally of the bit assures the cutting face of the bit of always having a cleaning and cooling fluid. This improved method enables the diamonds located in the cutting face of the bit to engage the formation at a smaller cutting depth, while still maintaining a satisfactory rate of penetration. Should the diamonds suddenly engage a harder or tougher formation, the individual diamonds will not be torn from the bit and lost.

As indicated by the arrow at numeral 90, the cutting face of the bit seats against the undrilled or remaining portion of the formation with an action similar to that of a valve; that is, when the bit bears against the formation with a large force, the pressure drop across the face of the bit must be increased in order to maintain the same flow rate of drilling fluid, and with the bit slightly displaced from the formation, a larger flow of fluid is required in order to maintain the same pressure drop. Therefore, the cooperation between the cutting face of the bit and the formation which is to be removed can be controlled by observation of the pressure drop as measured at 14.

As the core is cut, the fluid within the central tubing and core barrel is quiescent which eliminates the heretofore undesirable erosion or washing of the accumulated samples.

As a core is being cut (as illustrated at 28 in FIG- URE l), the core catcher (seen at 64 in FIGURE 2) travels upwardly within its housing as it expands to accept the core therethrough. The core catcher continues its upward travel until the upper edge portion of the core catcher abuts against face 55 of the barrel, thereby permitting the core to slide through the catcher and into the barrel. This action permits the edge portions 84 of the core catcher to expand with the core being forced therebetween and up into the barrel where it bears against the inwardly sloped face of the core breaker 58. The core breaker imparts suflicient sheer or lateral force into the core to cause it to break into uniform lengths whereupon the cores may accumulate or stack up within the core barrel until it is desired to circulate them back to the surface of the earth in the before described manner.

As further seen in FIGURE 2 in conjunction with FIGURE 1, the diamond bit is removably attached in a conventional manner to the outer tube 25 which in turn is threadedly attached to the sub 42 with the sub threadedly attaching the entire combination to the drill string. The entire device is easily broken down into its various components by merely removing the outer tube 25 and the inner tube connector 45 so as to enable the bearing 46 to be pressed therefrom. The core breaker and the lowerrnost member which contains the core catcher are threadedly disengaged from the main body of the core barrel by the indicated threaded connections.

The down time required for the coring operation of the present invention is negligible, which, coupled with the increased efficiency of operation brought about by utilizing the present method enables a substantial increase of footage drilled per unit of time.

While the core barrel of the present invention is of the non-rotating type, it is contemplated to use the present invention in conjunction with other types of core barrels.

While I have illustrated and described a preferred emmodiment of my invention it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What I claim is:

1. In a well drilling apparatus having a rotatable drill bit for cutting cores from formations, with the bit having a core receiving centrally located passageway therein and the bit being connected to concentrically arranged drilling pipe by a sub, and with the concentrically arranged pipe forming a central and an annular flow passageway for circulating drilling fluid to and from the bit, the improvement comprising:

said sub having a core barrel, means rotatably mounting said core barrel within said sub and between the bit passageway and the central passageway of the concentrically arranged pipe to enable said core barrel to receive cores which have been cut by the bit; a core catcher, means attaching said core catcher to said core barrel, said core catcher having means associated therewith for securing said core barrel to the core being cut by the bit to thereby prevent relative rotation between the core and the core barrel.

2. The improvement of claim 1 wherein a portion of said core barrel includes an inside peripheral wall surface having a downwardly and inwardly tapered portion which forms a core catcher housing, said core catcher being a circular expandable member having an outside peripheral wall portion adapted to be slidably received within said core catcher housing, a key means attached to said tapered portion of said barrel, said core catcher having means forming spaced apart edge portions, with said edge portions adapted to receive said key means therethrough, whereby cores cut by the bit are circumferentially surrounded by said core catcher as the core moves therethrough and into said barrel.

3. The improvement of claim 1 wherein said means attaching said core catcher to said barrel includes means by which it is secured to the lower inside marginal end portion of said core barrel in a manner to permit said core catcher to be slidably moved in a vertical direction and wherein said core catcher is secured against relative rotation with respect to said core barrel;

said means attaching said core catcher to said barrel having an inside surface formed with a multiplicity of splines to enable said core catcher to be expanded upon receiving a core therethrough.

4. The improvement of claim 1 wherein said means rotatably mounting said core barrel within said sub includes a journal attached between an upper marginal inside wall portion of the sub and an outside upper marginal wall portion of the core barrel to thereby form an annular passageway between the barrel and the sub; means forming a flow passageway from the annular flow pasasgeway of the concentrically arranged pipe, around said journal, and to the annular flow passageway of the drill pipe to thereby form the recited flow path to the drill bit.

5. In a sub for connecting a drill bit to a string of concentrically arranged drill pipe wherein the concentrically arranged pipe jointly form a central and an annular fiow passageway for circulating drilling fluid to and from the bit, and wherein the bit has a central passageway for receiving a core therethrough, the improvement comprising:

said sub having means forming a longitudinally extending central passageway adapted to be aligned with the drill string, a core barrel having means forming a longitudinally extending central passageway concentrically arranged with respect to the central passageway of the sub, with the core barrel being received within the central passageway of said sub and spaced apart from the inside peripheral wall surface of the sub to form a longitudinally extending annular passageway therebetween;

bearing means rotatably securing said core barrel to said sub; means forming a flow passageway from the annular passageway of the drill string to the annular passageway formed between said sub and said core barrel to enable fluid to flow around the bearing means;

means forming a lower guide means between said core barrel and said sub;

means forming a core catcher inside said core barrel for engaging a core as it is cut by the bit, and for securing the core to the core barrel to thereby prevent relative rotation between the core and the core barrel as the sub rotates the bit.

6. The improvement of claim 5 wherein said bit includes means forming grooves which forms a flow passageway between the lower terminal end of the barrel and the bore hole being formed by the bit to thereby enable fluid circulation to flow fromthe drill string annulus, through the annulus passageway of said sub, across the bit face, and to the well bore annulus and to also at the same time enable fluid to flow from the annular passageway of the sub, across the lower terminal end of the core barrel, and into the core barrel to thereby enable circulation of cores up through the central flow passageaway of the drill pipe.

7. The improvement of claim 5 wherein said core barrel includes a key attached thereto, said core catcher being a discontinuous member which includes edge portions which reciprocatingly receive the key therein;

means forming a core catcher housing at the lower extremity of said core barrel, said core catcher being reciprocatingly received within said housing with said key being slidably received between the edge portions of the core catcher to thereby enable said core catcher to be vertically moved within said housing while said key prevents said core catcher from rotating with respect to said core barrel.

8. The improvement of claim 7 wherein said core catcher housing has an inside wall surface which converges in a downward direction, said core catcher having an outside wall surface which defines an inverted frustocone, and the inside wall surface of the core catcher being in the form of a plurality of splines, whereby said core catcher can expand as it is forced in an upward direction by a core received therein.

9. In a well drilling apparatus including a dual-passage drill pipe arrangement having an outer pipe adapted to be rotated from the surface and a smaller inner tube supported within the outer pipe, said inner tube forming an inner flow passageway and the space between the inner tube and outer pipe forming an outer flow passageway, there being a coring bit having a central passageway therethrough secured to the bottom of the drill pipe arrangement by a drill sub, with the central passageway of the bit being in communication with the inner tube to enable cores cut by the bit to be circulated therethrough, and means for delivering drilling fluid in countercurrent flow relationship to and from the bit by said drill pipe arrangement, the improvement comprising:

means forming a core barrel within said bit sub, said barrel further including means by which it is rotatably mounted to said bit sub, means forming a central passageway through said core barrel for receiving cores from the central passageway of the bit and for delivering the cores to the inner tubing, means forming :a flow passageway from the space between the inner tube and outer pipe, around the core barrel and to the bit, means forming a flow passageway from the bit and into the core barrel; a core catcher, means attaching said core catcher to said core barrel, whereby;

said core catcher engages a core as it is passed through 9 10 the central passageway of the bit and into the core 3,323,604 6/1967 Henderson 175244 barrel to thereby prevent relative rotation between 3,338,322 8/1967 Henderson 175317 said core barrel and the core.

References Cited UNITED OTHER REFERENCES Unique Rig Cuts Continuous Cores, in World Oil,

STATES PATENTS 5 October 1965, vol. 161, No. 5, pp. 145447.

Wenensiek X DAVID H. BROWN, Primary Examiner Havlick 175-249 Grable 175-215 US. Cl. X.R. Henderson 175321 X 10 175-60, 252

Henderson 175215 

